(YELLOW-MARKED SPINE-TAIL.)
+Synallaxis sulphurifera+, _Hudson, P. Z. S._ 1872, p. 544 (Rio
Negro); _Scl. et Salv. Nomencl._ p. 64; _Scl. P. Z. S._ 1874,
p. 24; _Durnford, Ibis_, 1877, p. 180, et 1878, p. 61 (Buenos
Ayres); _Barrows, Bull. Nutt. Orn. Cl._ viii. p. 208 (Entrerios).
_Description._--Above brown, slightly olivaceous; wings blackish;
lesser wing-coverts, margins of the feathers of the greater
wing-coverts, and outer webs of the basal halves of the
wing-feathers pale chestnut; tail-feathers chestnut-brown, ends
much elongated and pointed; beneath white, throat and breast mottled
with grey, spot in middle of throat sulphur-yellow; flanks washed
with brown; bend of wing and under wing-coverts fulvous; bill and
feet pale horn-colour: whole length 6·3 inches, wing 2·1, tail 3·0.
_Female_ similar.
_Hab._ South Argentina and Patagonia.
I have found this _Synallaxis_, which was first described by Prof.
Burmeister, from specimens obtained near Buenos Ayres, in the swamps
along the Plata river; also on the Rio Negro, in Patagonia, where,
however, it is very scarce. It inhabits the dense rush-beds growing in
the water, where the _Limnornis curvirostris_ is also found. It closely
resembles that species in habits and language, and also assimilates to
it in colour and in the rather long, curved beak, sharp claws, stout
body, and short stiff tail. It is stationary, pairs for life, and lives
always closely concealed in its chosen bed of close-growing rushes. When
a person approaches their hiding-place the two birds creep up to the
summit of the rushes, protesting in peculiar, loud, angry rattling
notes. The _Limnornis_, which also pairs for life, has precisely the
same habit.
Durnford describes the nest, found in a rush-bed, as a circular or domed
structure of grass, with the aperture at the side; the eggs white.